1. Field of the Invention
The present invention relates to a cellular radio system comprising a base station controller and base stations connected to it. The invention further relates to a base station of a cellular radio system, comprising transmission units for transmitting communication signals to the base station controller and for receiving communication signals from the base station controller on a communication link, whereby the transmission units are arranged to feed a base station specific identification message to the base station controller by utilizing a predetermined communication channel in response to the base station initialization.
The term initialization in this context refers to a procedure carried out, for example, when the supply power is for the first time connected to the base station, after which the base station carries out initial functions programmed for it.
2. Description of Related Art
The invention relates to a communication network of a cellular radio system, such as the GSM (Groupe Special Mobile) or DCS (Digital Cellular System), and particularly to the communication link between base stations and the base station controller. The prior art technology recognizes cellular radio systems in which all base stations connected to the same communication link (a chain or a ring network), such as a 2 Mbit/s PCM connection, are assigned a dedicated, base station specific communication channel, i.e. a PCM (Pulse Code Modulation) time slot, which is utilized by the base stations as they for the first time establish a connection to the base station controller. This means that the base stations, in connection with the initialization following the installation, for example, from the very beginning establish contact to the base station controller on a base station specific O&M channel (Operation & Maintenance) assigned to them. In order for this to be possible, the person who installs the base station must, at the installation stage, feed data concerning the channel configuration of the system to the base station. In practice, this takes place so that the base station installer, during the installing, connects a portable microcomputer or a service terminal specifically intended for the initialization of transmission units to the base station, by means of which service terminal he feeds transmission branching tables of the system to the base station, indicating, among other things, which PCM time slots are allocated for use by the base station in question, and which PCM time slots the base station should repeat forward in the network.
The most serious weakness of the above-mentioned prior art solution is the difficulty concerning its application. In order for the installer to be able to feed the base station with correct data, he must have a considerable amount of information on the channel allocation of the network. In addition, it is difficult to correct any errors that may occur in the feeding process, because that would require another visit by the installer to the base station site (errors, if any, are usually detected only afterwards). If the configuring of a base station fails, for example, in connection with a reconfiguration of the network during, e.g., channel re-allocation, the installer must visit the base station site to feed the base station with the new data by means of the service terminal.